Welcome, guest | Sign In | My Account | Store | Cart

construct sql query in python rather than performing tons of string manipulation. Take a look at docstring of StandardSelect and OracleSelect for a hint on how the module should be used.

Python, 976 lines
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
try:
    frozenset
except NameError:
    from sets import ImmutableSet as frozenset

def indent(width, s):
    space = width * ' '
    return '\n'.join([(space + line) for line in s.split('\n')])

def make_indenter(width):
    def indenter(s): return indent(width, s)
    return indenter

class AutoIndent(object):
    r"""AutoIndent

    replace bracketed template '( %s )' with multi-line template that will
    block-indents elements when interpolated with parameter

        >>> s1 = AutoIndent('speak(%s)')
        >>> s2 = AutoIndent('speak( %s )')

        >>> word = 'hello'
        >>> paragraph = '\n'.join(['Hello !', 'How are you ?', 'It\'s nice to see you.'])
    
        >>> print s1 % word
        speak(hello)

        >>> print s2 % paragraph
        speak(
          Hello !
          How are you ?
          It's nice to see you.
        )
    """
    def __init__(self, template):
        super(AutoIndent, self).__init__()
        multiline = template.count('( %s )')
        if multiline and (multiline != template.count('%s')):
            raise ValueError('Template must be homogenious')
        self.template = template.replace('( %s )', '(\n%s\n)')
        if multiline:
            self.indent = make_indenter(2)
        else:
            self.indent = lambda x: x
    def __mod__(self, value):
        if isinstance(value, basestring):
            t = (self.indent(value),)
        else:
            t = tuple([self.indent(v) for v in value])
        return self.template % t

def multiline(s):
    r"""multiline

        >>> multiline('Hello there')
        False

        >>> multiline('\n'.join(['Hello', 'there']))
        True
    """
    return s.find('\n') >= 0

class Source(object):
    """Source

        >>> i = Source('items')
        >>> print i.ITEM_ID
        items.ITEM_ID
    """
    def __init__(self, alias):
        super(Source, self).__init__()
        self.alias = alias
        self.fields = {}
    def __getattr__(self, name):
        if name in self.fields:
            return self.fields[name]
        else:
            f = Field(self, name)
            self.fields[name] = f
            return f
    def __str__(self): return self.alias
    def declaration(self): raise NotImplementedError()

class StatementSource(Source):
    """StatementSource

        >>> s = StatementSource('items', 'select * from IMA')
        >>> print s.declaration()
        (
          select * from IMA
        ) items
    """
    def __init__(self, alias, statement):
        super(StatementSource, self).__init__(alias)
        self.statement = statement
    def declaration(self):
        return AutoIndent('( %s ) ') % str(self.statement) + self.alias

class NamedSource(Source):
    """NamedSource

        >>> i = NamedSource('items', 'i')
        >>> print i
        i
        >>> print i.ITEM_ID
        i.ITEM_ID
    """
    def __init__(self, name, alias=None):
        super(NamedSource, self).__init__(alias)
        self.name = name
    def __str__(self): return self.alias or self.name
    def declaration(self):
        if self.alias:
            return '%s %s' % (self.name, self.alias)
        else:
            return self.name

class Expression(object): pass

class CustomExpression(Expression):
    def __init__(self, text): self.text = text
    def __str__(self): return str(self.text)

custom = CustomExpression

class StringLiteralExpression(Expression):
    """StringLiteralExpression

        >>> s = StringLiteralExpression('Huh?')
        >>> print s
        'Huh?'
    """
    def __init__(self, text): self.text = text
    def __str__(self): return "'%s'" % (self.text.replace("'", "''"))
    def expression(cls, expr):
        if isinstance(expr, Expression) and not isinstance(expr, cls): return expr
        else: return cls(expr)
    expression = classmethod(expression)

strlit = StringLiteralExpression.expression

class BooleanExpression(Expression): pass

class UnaryOperated(object):
    def __init__(self, element):
        super(UnaryOperated, self).__init__()
        self.element = element
    def __nonzero__(self): return bool(self.element)

class BinaryOperated(object):
    def __init__(self, *elements):
        super(BinaryOperated, self).__init__()
        self.elements = elements
    def __len__(self): return len(self.elements)
    def __nonzero__(self):
        for e in self.elements:
            if e: return True
        return False

class IsNull(UnaryOperated, Expression):
    """IsNull

        >>> print IsNull('ITEM_ID')
        ITEM_ID is null
    """
    def __str__(self): return '%s is null' % str(self.element)

class Blanket(UnaryOperated, Expression):
    def __str__(self):
        s = str(self.element)
        if multiline(s): return AutoIndent('( %s )') % s
        else: return '(%s)' % s

def blanket(expression):
    """blanket

        >>> print blanket('Huh?')
        (Huh?)

        >>> print blanket(blanket('Huh?'))
        (Huh?)
    """
    if isinstance(expression, Blanket):
        return expression
    else:
        return Blanket(expression)

def is_composite(expr):
    """is_composite

        >>> is_composite(Not('1=1'))
        False
    
        >>> is_composite(And('1=1'))
        False

        >>> is_composite(And('1=1', '2=2'))
        True
    """
    return isinstance(expr, BinaryOperated) and (len(expr) > 1)

def blanket_as_needed(expression):
    """blanket_as_needed

        >>> print blanket_as_needed('Huh?')
        (Huh?)

        >>> print blanket_as_needed(Not('0=0'))
        not (0=0)

        >>> print blanket_as_needed(And('0=0', '1=1', '2=2'))
        (
          (0=0) and
          (1=1) and
          (2=2)
        )
    """
    if is_composite(expression) or isinstance(expression, basestring): return Blanket(expression)
    else: return expression


class Prefixed(UnaryOperated):
    def __init__(self, prefix, element):
        super(Prefixed, self).__init__(element)
        self.prefix = prefix
    def __str__(self): return '%s %s' % (self.prefix, str(blanket_as_needed(self.element)))

class Infixed(BinaryOperated):
    def __init__(self, infix, *elements):
        super(Infixed, self).__init__(*elements)
        self.infix = infix
    def __str__(self): return (' %s ' % self.infix).join([str(blanket_as_needed(e)) for e in self.elements if e])

class PrefixedExpression(Prefixed, Expression):
    def __init__(self, prefix, expression):
        Prefixed.__init__(self, prefix, expression)
        Expression.__init__(self)

class Plus(PrefixedExpression):
    def __init__(self, expression): super(Plus, self).__init__('+', expression)

class Minus(PrefixedExpression):
    def __init__(self, expression): super(Minus, self).__init__('-', expression)

class PrefixedBooleanExpression(Prefixed, BooleanExpression):
    def __init__(self, prefix, boolexpr):
        Prefixed.__init__(self, prefix, boolexpr)
        Expression.__init__(self)

class Not(Prefixed, BooleanExpression):
    """Not

        >>> print Not('0=0')
        not (0=0)
    """
    def __init__(self, boolexpr): super(Not, self).__init__('not', boolexpr)

def invert(boolexpr):
    """invert

        >>> print invert('0=0')
        not (0=0)
    
        >>> print invert(invert('0=0'))
        0=0
    """
    if isinstance(boolexpr, Not):
        return boolexpr.element
    else:
        return Not(boolexpr)

class Combinative(object):
    
    def combine(cls, *combinatives):
        args = []
        for c in combinatives:
            if type(c) is cls:
                args.extend([e for e in c.elements if e])
            else:
                args.append(c)
        return cls(*args)
    combine = classmethod(combine)

class InfixedExpression(Infixed, Expression):
    def __init__(self, infix, *expressions):
        Infixed.__init__(self, infix, *expressions)
        Expression.__init__(self)

class Add(InfixedExpression, Combinative):
    """Add

        >>> print Add(1,2,3)
        1 + 2 + 3

        >>> print Add.combine(1,2,3)
        1 + 2 + 3

        >>> print Add.combine(1, Add(2,3), 4)
        1 + 2 + 3 + 4
    """
    def __init__(self, *expressions): super(Add, self).__init__('+', *expressions)

class Sub(InfixedExpression):
    def __init__(self, *expressions): super(Sub, self).__init__('-', *expressions)

class Mul(InfixedExpression, Combinative):
    def __init__(self, *expressions): super(Mul, self).__init__('*', *expressions)

class Div(InfixedExpression):
    def __init__(self, *expressions): super(Div, self).__init__('/', *expressions)

class InfixedBooleanExpression(Infixed, BooleanExpression):
    def __init__(self, infix, *boolexprs):
        Infixed.__init__(self, infix, *boolexprs)
        BooleanExpression.__init__(self)
    def __str__(self): return (' %s\n' % self.infix).join([str(blanket(e)) for e in self.elements])

class And(InfixedBooleanExpression, Combinative):
    """And

        >>> print And('0=0', '1=1', '2=2')
        (0=0) and
        (1=1) and
        (2=2)
    """
    def __init__(self, *boolexprs): super(And, self).__init__('and', *boolexprs)

class Or(InfixedBooleanExpression, Combinative):
    def __init__(self, *boolexprs): super(Or, self).__init__('or', *boolexprs)

class InfixedComparisonExpression(Infixed, BooleanExpression):
    def __init__(self, infix, left, right):
        if isinstance(left, basestring): left = strlit(left)
        if isinstance(right, basestring): right = strlit(right)
        Infixed.__init__(self, infix, left, right)
        BooleanExpression.__init__(self)
    left = property(lambda self: self.elements[0])
    right = property(lambda self: self.elements[1])

class Like(InfixedComparisonExpression):
    """Like

        >>> print Like(custom('ITEM_NAME'), 'Staron%')
        ITEM_NAME like 'Staron%'
    """
    def __init__(self, value, pattern):
        super(Like, self).__init__('like', value, pattern)

class LessThan(InfixedComparisonExpression):
    """LessThan
    
        >>> lessthan = LessThan(1, 2)
        >>> print lessthan
        1 < 2
        >>> lessthan.left
        1
        >>> lessthan.right
        2
    """
    def __init__(self, left, right): super(LessThan, self).__init__('<', left, right)

class LessThanOrEqual(InfixedComparisonExpression):
    def __init__(self, left, right): super(LessThanOrEqual, self).__init__('<=', left, right)

class GreaterThan(InfixedComparisonExpression):
    def __init__(self, left, right): super(GreaterThan, self).__init__('>', left, right)

class GreaterThanOrEqual(InfixedComparisonExpression):
    def __init__(self, left, right): super(GreaterThanOrEqual, self).__init__('>=', left, right)

class Equal(InfixedComparisonExpression):
    def __init__(self, left, right): super(Equal, self).__init__('=', left, right)

class OracleOuterDecorator(InfixedComparisonExpression):
    def __init__(self, decorated, left_outer=True):
        super(OracleOuterDecorator, self).__init__(decorated.infix, decorated.left, decorated.right)
        self.decorated = decorated
        self.left_outer = left_outer
    def __str__(self):
        if self.left_outer:
            return '%s %s %s(+)' % (self.left, self.infix, self.right)
        else:
            return '%s(+) %s %s' % (self.left, self.infix, self.right)

class NotEqual(InfixedComparisonExpression):
    def __init__(self, left, right): super(NotEqual, self).__init__('<>', left, right)

class Field(Expression):
    r"""Field

        >>> name = Field('item', 'ITEM_NAME')
        >>> price = Field('item', 'PRICE')
        >>> cost = Field('item', 'COST')
        >>> quantity = Field('invoice', 'QUANTITY')
    
        >>> print '\n'.join([str(x) for x in [name, price, cost, quantity]])
        item.ITEM_NAME
        item.PRICE
        item.COST
        invoice.QUANTITY

        >>> print price > cost
        item.PRICE > item.COST

        >>> print price * quantity
        item.PRICE * invoice.QUANTITY

        >>> print name.like('Staron%')
        item.ITEM_NAME like 'Staron%'

        >>> print name.is_null
        item.ITEM_NAME is null
    """
    
    def __init__(self, source, fieldname):
        super(Field, self).__init__()
        self.source = source
        self.fieldname = fieldname
    def __str__(self): return '%s.%s' % (str(self.source), self.fieldname)
    def __add__(self, other): return Add(self, other)
    def __radd__(self, other): return Add(other, self)
    def __sub__(self, other): return Sub(self, other)
    def __rsub__(self, other): return Sub(other, self)
    def __mul__(self, other): return Mul(self, other)
    def __rmul__(self, other): return Mul(other, self)
    def __div__(self, other): return Div(self, other)
    def __rdiv__(self, other): return Div(other, self)
    def __pos__(self): return Plus(self)
    def __neg__(self): return Minus(self)
    def __pow__(self, other): raise NotImplementedError()
    def __rpow__(self, other): raise NotImplementedError()
    def __abs__(self): raise NotImplementedError()
    def __mod__(self, other): raise NotImplementedError()
    def __rmod__(self, other): raise NotImplementedError()
    def __lt__(self, other): return LessThan(self, other)
    def __le__(self, other): return LessThanOrEqual(self, other)
    def __gt__(self, other): return GreaterThan(self, other)
    def __ge__(self, other): return GreaterThanOrEqual(self, other)
    def __eq__(self, other): return Equal(self, other)
    def __ne__(self, other): return NotEqual(self, other)
    def __and__(self, other): return And(self, other)
    def __rand__(self, other): return And(other, self)
    def __or__(self, other): return Or(self, other)
    def __ror__(self, other): return Or(other, self)
    is_null = property(lambda self: IsNull(self))
    def like(self, other): return Like(self, other)

class SourceList(object):
    """SourceList

        >>> s = SourceList()
        >>> item = s('ITEMS')
        >>> print item
        ITEMS
    
        >>> s('ITEMS')
        Traceback (most recent call last):
          ...
        ValueError: Duplicated key ('ITEMS')
    """
    def __init__(self):
        super(SourceList, self).__init__()
        self.clear()
        
    def clear(self):
        self.keys = []
        self.exprs = []
        self.aliases = []
        
    def clone(self):
        r = SourceList()
        r.assign(self)
        return r
    
    def assign(self, other):
        self.keys = list(other.keys)
        self.exprs = list(other.exprs)
        self.aliases = list(other.aliases)
        
    def __str__(self):
        def line(expr, alias):
            if not alias: return str(expr)
            return '%s %s' % (str(expr), str(alias))
        return ',\n'.join([line(expr, alias) for expr, alias in zip(self.exprs, self.aliases)])

    def __iter__(self): return iter(self.exprs)
        
    def _append(self, expr, alias):
        if isinstance(expr, Source):
            key = str(expr)
        else:
            key = str(alias or expr)
        if key in self.keys: raise ValueError("Duplicated key ('%s')" % key)
        self.keys.append(key)
        self.exprs.append(expr)
        self.aliases.append(alias)
    def __call__(self, name, alias=None):
        result = NamedSource(name, alias)
        self._append(result, alias)
        return result
    def statement(self, alias, statement):
        result = StatementSource(alias, statement)
        self._append(result, alias)
        return result

def iter_fields(expression):
    r"""iter_fields

        >>> ima = NamedSource('ima')
        >>> wko = NamedSource('wko')
        >>> join = And(ima.IMA_ItemID == wko.WKO_ItemID,
        ...            ima.IMA_UnitMeasure == wko.WKO_UnitMeasure,
        ...            Or(ima.IMA_ItemPrice.is_null, wko.WKO_WorkOrderDate == 3))
        ...
        >>> print '\n'.join([str(x) for x in iter_fields(join)])
        ima.IMA_ItemID
        wko.WKO_ItemID
        ima.IMA_UnitMeasure
        wko.WKO_UnitMeasure
        ima.IMA_ItemPrice
        wko.WKO_WorkOrderDate
    """
    if isinstance(expression, Field):
        yield expression
    elif isinstance(expression, UnaryOperated) and isinstance(expression, Expression):
        for x in iter_fields(expression.element):
            yield x
    elif isinstance(expression, BinaryOperated) and isinstance(expression, Expression):
        for expr in expression.elements:
            for x in iter_fields(expr):
                yield x

class FieldList(object):
    """FieldList

        >>> fields = FieldList()

        >>> print fields
        <BLANKLINE>
    
        >>> sources = SourceList()
        >>> ima = sources('IMA')
        >>> wko = sources('WKO')
    
        >>> fields.append(ima.IMA_ItemID)
        >>> len(fields)
        1
        >>> fields.append(wko.IMA_ItemID)
        Traceback (most recent call last):
          ...
        ValueError: Duplicated key ('IMA_ItemID')

        >>> fields.append(wko.IMA_ItemID, 'ITEM_ID')
        >>> len(fields)
        2

        >>> fields.append(ima.WKO_ItemID, 'ITEM_ID')
        Traceback (most recent call last):
          ...
        ValueError: Duplicated key ('ITEM_ID')

        >>> len(fields)
        2

        >>> fields.append('getdate()', 'TODAY')
        >>> len(fields)
        3
        >>> print fields
        IMA.IMA_ItemID                                     IMA_ItemID,
        WKO.IMA_ItemID                                     ITEM_ID,
        getdate()                                          TODAY

        >>> fields = FieldList()
        >>> fields.append(ima.IMA_ItemID)
        >>> fields.append(wko.WKO_ItemID)
        >>> fields.append('DATE')
        >>> print fields
        IMA.IMA_ItemID,
        WKO.WKO_ItemID,
        DATE
    """
    def __init__(self):
        super(FieldList, self).__init__()
        self.clear()
    def clear(self):
        self.keys = []
        self.values = []
        self.aliases = []
    def clone(self):
        r = FieldList()
        r.assign(self)
        return r
    def assign(self, other):
        self.keys = list(other.keys)
        self.values = list(other.values)
        self.aliases = list(other.aliases)
    def __len__(self): return len(self.keys)
    def __str__(self):
        if self.some_was_aliased():
            def line(key, value, alias): return '%-50s %s' % (str(value), str(key or alias or value))
            return ',\n'.join([line(k,v,a) for k,v,a in zip(self.keys, self.values, self.aliases)])
        else:
            return ',\n'.join([str(v) for v in self.values])
    def _check_key(self, key):
        if (key is not None) and (key in self.keys):
            raise ValueError("Duplicated key ('%s')" % key)
    def _do_append(self, key, value, alias):
        self._check_key(key)
        self.keys.append(key)
        self.values.append(value)
        self.aliases.append(alias)
    def _append_value(self, value, alias): self._do_append(alias, value, alias)
    def _append_field(self, field, alias): self._do_append(alias or field.fieldname, field, alias)
    def some_was_aliased(self):
        return [a for a in self.aliases if a is not None]
    def append(self, value, alias=None):
        if isinstance(value, Field):
            self._append_field(value, alias)
        else:
            self._append_value(value, alias)

class BooleanExpressionList(object):
    """BooleanExpressionList

        >>> exprs = BooleanExpressionList()
        >>> print exprs
        <BLANKLINE>

        >>> exprs.And('1=1')
        >>> print exprs
        (1=1)

        >>> exprs.invert()
        >>> print exprs
        not (1=1)

        >>> exprs.invert()
        >>> print exprs
        (1=1)

        >>> exprs.And('2=2')
        >>> print exprs
        (1=1) and
        (2=2)

        >>> exprs.Or('3=3', '4=4', '5=5')
        >>> print exprs
        (
          (1=1) and
          (2=2)
        ) or
        (3=3) or
        (4=4) or
        (5=5)

        >>> exprs.Or('6=6', '7=7')
        >>> print exprs
        (
          (1=1) and
          (2=2)
        ) or
        (3=3) or
        (4=4) or
        (5=5) or
        (6=6) or
        (7=7)
    """
    def __init__(self):
        super(BooleanExpressionList, self).__init__()
        self.clear()
    def clear(self): self.root = None
    def clone(self):
        r = BooleanExpressionList()
        r.assign(self)
        return r
    def assign(self, other):
        import copy
        self.root = copy.deepcopy(other.root)
    def __str__(self): return str(self.root or '')
    def _append(self, booloper, *boolexprs):
        if len(boolexprs) > 0:
            if self.root is None:
                self.root = booloper(*boolexprs)
            else:
                self.root = booloper.combine(self.root, *boolexprs)
    def And(self, *boolexprs): self._append(And, *boolexprs)
    def Or(self, *boolexprs): self._append(Or, *boolexprs)
    def invert(self):
        if self.root is not None: self.root = invert(self.root)

class GroupByList(object):
    """GroupByList

        >>> groupby = GroupByList()
    
        >>> print groupby
        <BLANKLINE>
    
        >>> groupby.append('INVO_DATE')
        >>> groupby.append('ORDER_DATE')
        >>> print groupby
        INVO_DATE,
        ORDER_DATE
    """
    def __init__(self):
        super(GroupByList, self).__init__()
        self.clear()
    def clear(self): self.values = []
    def clone(self):
        r = GroupByList()
        r.assign(self)
        return r
    def assign(self, other): self.values = list(other.values)
    def append(self, value): self.values.append(value)
    def __str__(self):
        return ',\n'.join([str(v) for v in self.values])

class OrderByList(object):
    """OrderByList

        >>> orderby = OrderByList()
    
        >>> print orderby
        <BLANKLINE>
    
        >>> orderby.append('INVO_DATE')
        >>> orderby.append('ORDER_DATE', False)
        >>> orderby.append('LINE_NUMBER', True)
        >>> print orderby
        INVO_DATE,
        ORDER_DATE desc,
        LINE_NUMBER
    """
    def __init__(self):
        super(OrderByList, self).__init__()
        self.clear()
    def clear(self):
        self.values = []
        self.ascendings = []
    def clone(self):
        r = OrderByList()
        r.assign(self)
        return r
    def assign(self, other):
        self.values = list(other.values)
        self.ascendings = list(other.ascendings)
    def append(self, value, ascending=True):
        self.values.append(value)
        self.ascendings.append(ascending)
    def __str__(self):
        def line(value, ascending): return (ascending and str(value)) or (str(value) + ' desc')
        return ',\n'.join([line(v,a) for v,a in zip(self.values, self.ascendings)])

class Function(object):
    def __init__(self, name):
        super(Function, self).__init__()
        self.name = name
    def __call__(self, *args):
        args_text = ', '.join([blanket_as_needed(a) for a in args])
        return '%s(%s)' % (self.name, args_text)

class FunctionFactory(object):
    def __getattr__(self, name): return Function(name)

class Statement(object):
    def __init__(self):
        super(Statement, self).__init__()
        self.func = FunctionFactory()

class BaseJoinList(object):
    def __init__(self):
        super(BaseJoinList, self).__init__()
        self.clear()
    def clear(self):
        self.lefts = []
        self.rights = []
        self.expressions = []
    def clone(self):
        r = type(self)()
        r.assign(self)
        return r
    def assign(self, other):
        self.lefts = list(other.lefts)
        self.rights = list(other.rights)
        self.expressions = list(other.expressions)
    def is_joined(self, left, right): raise NotImplementedError()
    def append(self, left, right, expression):
        if self.is_joined(left, right): raise ValueError('Already joined')
        sources = frozenset([f.source for f in iter_fields(expression)])
        if (len(sources) != 2) or (left not in sources) or (right not in sources):
            raise ValueError('Only expressions of fields of joining sources are allowed')
        self.lefts.append(left)
        self.rights.append(right)
        self.expressions.append(expression)
    def iter_joinings(self, joined): raise NotImplementedError()

class InnerJoinList(BaseJoinList):
    def __init__(self): super(InnerJoinList, self).__init__()
    def is_joined(self, left, right):
        for l,r in zip(self.lefts, self.rights):
            if (l==left) and (r==right): return True
            if (l==right) and (r==left): return True
        return False
    def iter_joinings(self, joined):
        for i in xrange(len(self.lefts)):
            if self.lefts[i]==joined: yield self.rights[i], self.expressions[i]
        for i in xrange(len(self.rights)):
            if self.rights[i]==joined: yield self.lefts[i], self.expressions[i]

class OuterJoinList(BaseJoinList):
    def __init__(self): super(OuterJoinList, self).__init__()
    def is_joined(self, left, right):
        for l,r in zip(self.lefts, self.rights):
            if (l==left) and (r==right): return True
        return False
    def iter_joinings(self, joined):
        for i in xrange(len(self.lefts)):
            if self.lefts[i]==joined: yield self.rights[i], self.expressions[i]

def make_oracle_outer(outer, inner, expression):
    if isinstance(expression, InfixedComparisonExpression) and (not isinstance(expression, OracleOuterDecorator)):
        if (expression.left == outer) and (expression.right == inner): return OracleOuterDecorator(expression, True)
        if (expression.left == inner) and (expression.right == outer): return OracleOuterDecorator(expression, False)
	raise Exception('Not supported expression')
    elif isinstance(expression, InfixedBooleanExpression):
        return type(expression)(*[make_oracle_outer(outer, inner, e) for e in expression.elements])

class BaseSelect(Statement):
    def __init__(self):
        super(BaseSelect, self).__init__()
        self.fields = FieldList()
        self.sources = SourceList()
        self.where = BooleanExpressionList()
        self.groupby = GroupByList()
        self.having = BooleanExpressionList()
        self.orderby = OrderByList()
        self.innerjoins = InnerJoinList()
        self.outerjoins = OuterJoinList()

    def get_from_clause(self): raise NotImplementedError()

    def get_where_clause(self): raise NotImplementedError()

    def __str__(self):
        def section(term, clause):
            if clause:
                return '%s\n%s' % (term, indent(2, clause))
            else:
                return ''
        fields = str(self.fields) or '*'
        froms = section('from', self.get_from_clause())
        where = section('where', self.get_where_clause())
        groupby = section('group by', str(self.groupby))
        having = section('having', str(self.having))
        orderby = section('order by', str(self.orderby))
        return '\n'.join([x for x in ['select', indent(2, fields), froms, where, groupby, having, orderby] if x])

    def join(self, left, right):
        def joiner(*exprs): self.innerjoins.append(left, right, And(*exprs))
        return joiner
    def outer_join(self, left, right):
        def joiner(*exprs): self.outerjoins.append(left, right, And(*exprs))
        return joiner

class StandardSelect(BaseSelect):
    """StandardSelect

        >>> s = StandardSelect()
        >>> ima = s.sources('ima')
        >>> pst = s.sources('pst')
        >>> ima2 = s.sources('ima', 'ima2')
        >>> s.join(ima, pst)(ima.IMA_ItemID == pst.PST_ItemID)
        >>> s.outer_join(ima, ima2)(ima.IMA_ItemID == ima2.IMA_ItemID)
        >>> s.where.And(ima.ItemCost > 100000)
        >>> s.where.And(ima.ItemCost < 200000)
        >>> s.fields.append(ima.IMA_ItemID, 'ID')
        >>> s.fields.append(ima.IMA_ItemCost, 'COST')
        >>> s.fields.append(ima.IMA_ItemName, 'ITEM_NAME')
        >>> s.groupby.append(ima.IMA_ItemID)
        >>> s.groupby.append(ima.IMA_ItemCost)
        >>> s.groupby.append(ima.IMA_ItemName)
        >>> s.having.And(ima.IMA_ItemName.like(strlit('Huh%')))
        >>> s.orderby.append(ima.IMA_ItemName, False)
        >>> s.orderby.append(ima.IMA_ItemCost)
        >>> print s
        select
          ima.IMA_ItemID                                     ID,
          ima.IMA_ItemCost                                   COST,
          ima.IMA_ItemName                                   ITEM_NAME
        from
          ima
            join pst on (ima.IMA_ItemID = pst.PST_ItemID)
            left outer join ima ima2 on (ima.IMA_ItemID = ima2.IMA_ItemID)
        where
          (ima.ItemCost > 100000) and
          (ima.ItemCost < 200000)
        group by
          ima.IMA_ItemID,
          ima.IMA_ItemCost,
          ima.IMA_ItemName
        having
          (ima.IMA_ItemName like 'Huh%')
        order by
          ima.IMA_ItemName desc,
          ima.IMA_ItemCost
    """

    def get_where_clause(self): return str(self.where)
    def get_from_clause(self):
        result = []
        included = []
        for source in self.sources:
            if source not in included:
                queued = [source]
                joinlines = []
                while queued:
                    s = queued.pop(0)
                    if s not in included:
                        included.append(s)
                        for joining, expression in self.innerjoins.iter_joinings(s):
                            if joining not in included:
                                queued.append(joining)
                                joinlines.append('join %s on %s' % (joining.declaration(), str(expression)))
                        for joining, expression in self.outerjoins.iter_joinings(s):
                            if joining not in included:
                                queued.append(joining)
                                joinlines.append('left outer join %s on %s' % (joining.declaration(), str(expression)))
                    included.append(s)
                if result: result[-1] += ','
                result.append(str(source))
                result.extend(['  %s' % x for x in joinlines])
        return '\n'.join(result)

class OracleSelect(BaseSelect):
    """OracleSelect

        >>> s = OracleSelect()
        >>> ima = s.sources('ima')
        >>> pst = s.sources('pst')
        >>> ima2 = s.sources('ima', 'ima2')
        >>> s.join(ima, pst)(ima.IMA_ItemID == pst.PST_ItemID)
        >>> s.outer_join(ima, ima2)(ima.IMA_ItemID == ima2.IMA_ItemID)
        >>> s.where.And(ima.ItemCost > 100000)
        >>> s.where.And(ima.ItemCost < 200000)
        >>> print s
        select
          *
        from
          ima,
          pst,
          ima ima2
        where
          (ima.IMA_ItemID = pst.PST_ItemID) and
          (ima.IMA_ItemID = ima2.IMA_ItemID(+)) and
          (ima.ItemCost > 100000) and
          (ima.ItemCost < 200000)
    """
    def get_where_clause(self):
        inner_exprs = self.innerjoins.expressions
        outer_packs = zip(self.outerjoins.lefts, self.outerjoins.rights, self.outerjoins.expressions)
        outer_exprs = [make_oracle_outer(outer, inner, expr) for outer, inner, expr in outer_packs]
        if self.where.root:
            where_exprs = [self.where.root]
        else:
            where_exprs = []
        return str(And.combine(*(inner_exprs + outer_exprs + where_exprs)))
    
    def get_from_clause(self): return ',\n'.join([source.declaration() for source in self.sources])
    
if __name__ == '__main__':
    try:
        from zope.testing import doctest
    except ImportError:
        import doctest
    doctest.testmod()

This module can make 80% of dynamic sql construction easier and it makes your code be in better factored shape. The module is fully doctested. Sorry if you find the tables and fields' name used in the doctest string is a bit ugly. It's from my current work. I don't name table and fields that way, btw.

2 comments

Mike Hostetler 16 years, 6 months ago  # | flag

SQLObject. for something somewhat similar, check out the SQLObject project:

http://www.sqlobject.org

It's different, because it does all the SQL calls in the background and returns the results as Python objects. Works well if you are using the one of the supported databases. The above is a less db-platform-specific solution.

Patrick Tou 15 years, 2 months ago  # | flag

bug report. While simple, this module mostly serves my purposes. Bug report:

# diff standardselect.py standardselect_orig.py
233c233
&lt;     def __str__(self): return (' %s ' % self.infix).join([str(blanket_as_needed(e)) for e in self.elements if str(e).strip != ""])
---
&gt;     def __str__(self): return (' %s ' % self.infix).join([str(blanket_as_needed(e)) for e in self.elements if e])
877d876
&lt;         &gt;&gt;&gt; s.where.And(ima.ItemCount == 0)
898,899c897
&lt;           (ima.ItemCost &lt; 200000) and
&lt;           (ima.ItemCount = 0)
---
&gt;           (ima.ItemCost &lt; 200000)